Does the J2EE connector architecture relate to B2B in anyway or is it just a connecting mechanism to talk to legacy apps inside the house?
The J2EE Connector Architecture provides a general purpose connection pooling, inbound & outbound messaging and transaction handling. The JavaDoc for JCA is here...http://java.sun.com/j2ee/1.4/docs/api/javax/resource/spi/package-summary.html
You can use an embedded JCA container here...http://jencks.org/
Also there is JCA CCI which provides access to legacy applications like CICS etc.http://java.sun.com/j2ee/1.4/docs/api/javax/resource/cci/package-summary.html